Hardware improvements and methods for the analysis of a spinning reflective substrates

ABSTRACT

Embodiments of systems and methods for monitoring one or more characteristics of a substrate are disclosed. Various embodiments of utilizing optical sensors (in one embodiment a camera) to provide data regarding characteristics of a fluid dispensed upon the substrate are described. A variety of hardware improvements and methods are provided to improve the collection and analysis of the sensor data. More specifically, a wide variety of hardware related techniques may be utilized, either in combination or singularly, to improve the collection of data using the optical sensor. These hardware techniques may include improvements to the light source, improvements to the optical sensors, the relationship of the physical orientation of the light source to the optical sensor, the selection of certain pixels of the image for analysis, and the relationship of the optical sensor frame rate with the rotational speed of the substrate.

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/957,481, entitled, “Hardware Improvements and Methods for theAnalysis of Spinning Reflective Substrates,” filed Jan. 6, 2020; thedisclosure of which is expressly incorporated herein, in its entirety,by reference.

BACKGROUND

The present disclosure relates to the processing of substrates. Inparticular, it provides a novel system and method for monitoring one ormore characteristics of a substrate processing step. In one embodiment,the system and method disclosed herein may be utilized when processingsemiconductor substrates.

Traditional substrate processing systems utilize photolithographyprocesses, which include photoresist coating, exposure, photoresistdevelop, and various bake steps. The materials and processes utilized inthese steps may all impact film thickness, critical dimension targeting,line roughness, uniformity, etc. on a substrate. As geometries insubstrate processing continue to shrink, the technical challenges toforming structures on substrates increase. These processes utilize fluiddispense systems at various photolithography process steps. Fluiddispense systems may also be utilized to apply fluids and/or formcoatings at other process steps in a substrate processing flow.

Gross processing equipment excursions or faults such as equipmentbreakdowns, material drips, improper arm movements, etc. in fluiddispense systems are known to be monitored. One approach for monitoringgross processing issues in coating modules has been the inclusion of acamera in a coating module of a processing system. For example, coatingmodules have included spin module monitor (SMM) cameras which can beused to identify drips of the material being coated, improper dispensearm movements, etc. Images from the SMM camera may be analyzed afterprocessing to determine if a substrate was subjected to such processexcursions or faults.

SUMMARY

Various embodiments of systems and methods for monitoring one or morecharacteristics of a substrate are disclosed herein. More specifically,the present disclosure provides various embodiments of utilizing opticalsensors to provide information regarding characteristics of a fluiddispense system. In one embodiment, the optical sensor may be a cameraused for obtaining video images and/or still images from the substrate.However, the optical sensor may be any type of other optical sensorsthat obtain spectral data, for a given wavelength or range ofwavelengths, from a substrate. For example, other optical sensorssuitable for use within the fluid dispense system disclosed hereininclude, but are not limited to, spectrometers and sensors oflaser-based transceivers. Thus, though described herein with regard toone embodiment of an optical sensor which is a camera, it will berecognized that the techniques described herein are also applicable toother optical sensors and not limited to cameras. Thus, the use of acamera as the sensor in the embodiments discussed below is merelyexemplary and non-limiting. The optical sensors may be utilized tocollect video images, still images, spectrophotometric signals, opticalpower signals, etc.

As disclosed herein, a variety of hardware improvements and methods areprovided to improve the collection and analysis of the optical sensordata. More specifically, as described below, a wide variety of hardwarerelated techniques may be utilized, either in combination or singularly,to improve the collection of data using the optical sensor system (forexample a camera). These hardware techniques may include improvements tothe light source, improvements to the sensors of the optical sensor, therelationship of the physical orientation of the light source to theoptical sensor, the selection of certain pixels of the image foranalysis, and the relationship of the optical sensor frame rate with therotational speed of the substrate. These hardware improvements mayprovide improved film thickness measurement capabilities and reducesignal noise in the data.

In a first embodiment, the light source may be chose so as to supplylonger wavelengths of light to assist in minimizing multiple wavelengthssimultaneously having interference effects. Specifically, the lightsource may be chosen to have wavelengths near the absorptioncapabilities/limitation of the optical sensor (on the high wavelengthside). This provides benefits from an increase in signal to noise as thenature of the periods of constructive and destructive interference hasincreased which means it is less likely to have the situation of thegreatest common multiple creating thicknesses in which multiplewavelengths from the light source having interference simultaneously.

In one alternative of the first embodiment, a method of monitoring oneor more characteristics of a fluid dispense system is provided. Themethod may comprise providing a substrate within the fluid dispensesystem; providing an optical sensor, the optical sensor having anoptical range of detected wavelengths; providing a light source, thelight source providing wavelengths in only an upper 50 percent of theoptical range; and obtaining data from the optical sensor to monitor acondition of a fluid dispensed on the substrate.

In another alternative of the first embodiment, a fluid dispense systemfor coating a film on a substrate is provided. The fluid dispense systemmay comprise a chuck capable of holding the substrate; a nozzle capableof dispensing one or more fluids onto the substrate; an optical sensor,the optical sensor having an optical range of detected wavelengths; alight source, the light source providing wavelengths in only an upper 50percent of the optical range; and a controller coupled to the opticalsensor, the controller configured to receive data from the opticalsensor regarding light reflected from the substrate when the one or morefluids are dispensed on the substrate.

In the alternatives of the first embodiment, the optical sensor may be acamera. In some alternatives, the light source provides wavelengths inonly an upper 20 percent of the optical range.

In a second embodiment, the optical sensor and the light source may beco-optimized by configuring the optical sensor so as not to exclude(such as exclusion by a filter) the higher wavelengths provided by thelight source. In one embodiment, a CMOS (complementary metal oxidesemiconductor)/charged coupled device (CCD) camera without the presenceof a filter is utilized. In one embodiment, the light source and cameracombination may operate in the near-infrared (NIR) and/orshortwave-infrared (SWIR) spectrums.

In one alternative of the second embodiment, a method of monitoring oneor more characteristics of a fluid dispense system is provided. Themethod may comprise providing a substrate within the fluid dispensesystem; providing a camera, the camera configured to receive wavelengthsof light in the near infrared spectrum or higher; providing a lightsource, the light source providing wavelengths in the near infraredspectrum or higher; and obtaining data from the camera at wavelengths inthe near infrared spectrum or higher to monitor a condition of a fluiddispensed on the substrate.

In another alternative of the second embodiment, a fluid dispense systemfor coating a film on a substrate is provided. The fluid dispense systemmay comprise a chuck capable of holding the substrate; a nozzle capableof dispensing one or more fluids onto the substrate; a camera, thecamera configured to receive wavelengths of light in the near infraredspectrum or higher; a light source, the light source providingwavelengths in the near infrared spectrum or higher; and a controllercoupled to the camera, the controller configured to receive data fromthe camera regarding light reflected from the substrate when the one ormore fluids are dispensed on the substrate.

In the alternatives of the second embodiment, the camera may be a CMOScamera or a CCD camera. Further, the light source may providewavelengths in a short wavelength infrared spectrum or higher. Thecamera may be an Indium Gallium Arsenide based camera.

In a third embodiment, filtering may be utilized to limit instances inwhich multiple wavelengths interfere simultaneously. Specifically,optical filters may be provided in the optical light path between thelight source and the optical sensor to reduce the spectral range of theutilized light. Moreover, multiple filters may be provided in the systemso that the amount of filtering may be selectively changed. Changes tothe filtering may be dependent upon the materials being coated and/orthe underlying substrate materials.

In one alternative of the third embodiment a method of monitoring one ormore characteristics of a fluid dispense system is provided. The methodmay comprise providing a substrate within the fluid dispense system;providing a light source having a spectral range of wavelengths;providing an optical sensor, the optical sensor receiving light from thelight source that is reflected off the substrate; providing a filter inan optical light path between the light source and the optical sensor;the filter narrowing a received spectral range of light received by theoptical sensor; and obtaining data from the optical sensor to monitor acondition of a fluid dispensed on the substrate.

In another alternative of the third embodiment, a fluid dispense systemfor coating a film on a substrate is provided. The fluid dispense systemmay comprise a chuck capable of holding the substrate; a nozzle capableof dispensing one or more fluids onto the substrate; an optical sensor;a light source, an optical light path between the light source and theoptical sensor so that the optical sensor may receive light from thelight source that is reflected off the substrate; a filter in theoptical light path between the light source and the optical sensor, thefilter narrowing a received spectral range of light received by theoptical sensor; and a controller coupled to the optical sensor, thecontroller configured to receive data from the optical sensor regardinglight reflected from the substrate when the one or more fluids aredispensed on the substrate.

In the alternatives of the third embodiment, the optical sensor may be acamera. Further, the filter may be located in a portion of the opticallight path between the substrate and the camera. In addition, the fluiddispense system may comprise a plurality of filters, the filters beingcapable of being selectably placed in the optical light path so as tochange the received spectral range of light received by the camera. Insome embodiments. The selection of one or more of the plurality offilters is based upon a fluid being dispensed and/or a material of thesubstrate.

In a fourth embodiment, the orientation and physical relationship of thelight source and optical sensor may be controlled. Specifically, thelight source and the optical sensor may be arranged so that one of morethe following conditions exist: 1) maintaining a similar angle to areference plane (that is parallel to the substrate plane) of the lightsource and the optical sensor, 2) maintaining a similar distancerelationship of the light source to the center of substrate and thecenter of substrate to optical sensor and 3) having the optical sensorpositioned 180 degrees diagonally across from light source. Suchconditions help ensure the 0^(th) order reflection of light from thesubstrate is obtained and minimize light diffraction effects which maybe caused by the underlying substrate.

In one alternative of the fourth embodiment a method of monitoring oneor more characteristics of a fluid dispense system is provided. Themethod may comprise providing a substrate within the fluid dispensesystem; providing a light source; providing an optical sensor, theoptical sensor receiving light from the light source that is reflectedoff the substrate; arranging a physical location of the optical sensorand the light source so that a 0^(th) order reflection of the light thatis reflected off the substrate is received by the optical sensor; andobtaining data from the optical sensor to monitor a condition of a fluiddispensed on the substrate.

In another alternative of the fourth embodiment, a fluid dispense systemfor coating a film on a substrate is provided. The fluid dispense systemmay comprise a chuck capable of holding the substrate; a nozzle capableof dispensing one or more fluids onto the substrate; an optical sensor;a light source, an optical light path between the light source and theoptical sensor so that the optical sensor may receive light from thelight source that is reflected off the substrate, the optical sensor andthe light source physically located so that the optical light pathincludes 0^(th) order reflection at the optical sensor of the light thatis reflected off the substrate; and a controller coupled to the opticalsensor, the controller configured to receive data from the opticalsensor regarding light reflected from the substrate when the one or morefluids are dispensed on the substrate.

In alternatives of the fourth embodiment, the optical sensor may be acamera. In some embodiments, an angle of incidence of the light from thelight source that is provided to the substrate and an angle of incidenceof the light reflected from the substrate that is provided to the camerais approximately the same. Further, in some embodiments, the lightsource and the camera are located approximately an equidistance from acenter of the substrate. In some embodiments, the light source and thecamera are located in the fluid dispense system so as to be diagonallylocated from each other with reference to the substrate.

In a fifth embodiment, rather than using all pixels reflected from asubstrate, only a subset of pixels is utilized for data processing. Thesubset of pixels may be chosen so as to minimize sources of image noiseand also exclude non 0^(th) order reflections. This may be accomplishedby limiting the selected pixels to those pixels in close proximity tothe observable primary reflection of the light source.

In one alternative of the fifth embodiment a method of monitoring one ormore characteristics of a fluid dispense system is provided. The methodmay comprise providing a substrate within the fluid dispense system;providing a light source; providing a camera, the camera receiving lightfrom the light source that is reflected off the substrate; and couplinga controller to the camera, the controller configured to receive datafrom the camera regarding light reflected from the substrate when one ormore fluids are dispensed on the substrate, the controller processingthe data so as to selectively consider only a subset of pixels of thedata from the camera to monitor a condition of a fluid dispensed on thesubstrate.

In some alternatives of the fifth embodiment the use of only a subset ofpixels of the data provides an output having less noise than if allavailable pixels are used. Further the subset of pixels selectedincludes the 0^(th) order reflection of light reflected off thesubstrate.

In a sixth embodiment, a sampling rate of the optical sensor issynchronized to match the substrate rotational speed. Suchsynchronization allows for each sample to be obtained from the same areaof the substrate. By performing this synchronization, diffractioneffects which may result from obtaining samples from differing areas ofthe substrate may be minimized.

In one alternative of the sixth embodiment, a method of monitoring oneor more characteristics of a fluid dispense system is provided. Themethod may comprise providing a chuck within the fluid dispense system,the chuck being configured to spin; providing a substrate within thefluid dispense system; spinning the chuck at a first revolutions perminute; providing a light source; providing an optical sensor, theoptical sensor receiving light from the light source that is reflectedoff the substrate, the optical sensor sampling received light at a firstsampling rate; synchronizing the first revolutions per minute to thefirst sampling rate; and obtaining data from the optical sensor tomonitor a condition of a fluid dispensed on the substrate.

In another alternative of the sixth embodiment, a fluid dispense systemfor coating a film on a substrate is provided. The fluid dispense systemmay comprise a spin chuck capable of holding the substrate; a nozzlecapable of dispensing one or more fluids onto the substrate; an opticalsensor; and a light source; one or more controllers coupled to theoptical sensor and the spin chuck, the one or more controllersconfigured to synchronize a rate of spinning of the spin chuck to asampling rate of the optical sensor. The at least one of the one or morecontrollers is configured to receive data from the optical sensorregarding light reflected from the substrate when the one or more fluidsare dispensed on the substrate.

In some alternatives of the sixth embodiment, the optical sensor is acamera. In some embodiments the synchronizing of the first revolutionsper minute (or the rate of spinning of the spin chuck) to the firstsampling rate provides for a plurality of frames of data to be collectedby the camera so that the substrate is in a same rotational orientationfor each of the plurality of frames.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present inventions and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, in which like referencenumbers indicate like features. It is to be noted, however, that theaccompanying drawings illustrate only exemplary embodiments of thedisclosed concepts and are therefore not to be considered limiting ofthe scope, for the disclosed concepts may admit to other equallyeffective embodiments.

FIG. 1 is an exemplary fluid dispense system.

FIG. 2 illustrates exemplary camera locations for the fluid dispensesystem of FIG. 1.

FIG. 3 illustrates exemplary light locations for the fluid dispensesystem of FIG. 1.

FIG. 4 illustrates a plot of reflectivity versus resist thickness forwavelength assumptions.

FIG. 5 illustrates a physical placement relationship of a light source,camera and substrate.

FIG. 6 illustrates alternative placements of a camera and light source.

FIG. 7 illustrates plots of a reflectivity intensity versus frames fordiffering selections of pixels.

FIGS. 8A-8C illustrate the pixel locations analyzed in differing frameswhen the camera frame rate is not synchronized to the substrate spinspeed.

FIGS. 9A-9C illustrate the pixel locations analyzed in differing frameswhen the camera frame rate is synchronized to the substrate spin speed.

FIGS. 10-15 illustrate methods for utilizing exemplary embodiments ofthe techniques described herein.

DETAILED DESCRIPTION

The techniques described herein may be utilized within a wide variety offluid dispense systems. For example, an exemplary fluid dispense systemmay be utilized for various fluid dispense purposes (such as, forexample, a resist coating unit, a resist developing unit, or other spincoating units) within which fluid are applied to a substrate forprocessing purposes. It is recognized that the fluid dispense systemsshown herein are merely exemplary embodiments of a processing systemwithin which the monitoring techniques described herein may be applied.Thus, the techniques disclosed herein may be applied to other fluiddispense systems and/or other processing units. Moreover, these fluiddispense systems may be stand-alone units or more be integrated in alarger systems. For example, the fluid dispense systems described hereinmay be integrated within larger systems that include coating,developing, baking, inspection, exposure, etc. modules.

The fluid dispense systems described herein may be utilized to subjectsubstrates to a wide variety of processing liquids, which may be partof, for example, resist coating unit, a developing unit or other fluiddispense systems (such as for example, spin-on hard mask units, spin-onanti-reflective coating units, etc.). As shown in FIG. 1, a fluiddispense system 60 includes a processing chamber, which is bounded by achamber walls 62. A spin chuck 64 disposed inside chamber walls 62provides support for a substrate, which may in some embodiments, be asemiconductor wafer (W). More specifically, the spin chuck 64 has ahorizontal upper surface on which the substrate is supported duringprocessing. A suction port (not shown) may be provided in the horizontalupper surface of spin chuck 64 for securing the substrate to the spinchuck with suction. The spin chuck 64, and the substrate supported bythe spin chuck 64, may be rotated at a variable angular velocity by adrive mechanism 66, which may be a stepper motor, etc. The drivemechanism 66 may operate at various angular velocities for theapplication of the liquid material and flow of the liquid material ontothe substrate.

A nozzle 68 is adapted to dispense one or more liquid solutions onto thesubstrate at a specified rate to apply one or more layers or films ontoan upper surface of the substrate. Typical layers or films that may beapplied to the substrate surface include, but are not limited to,imaging layers (e.g., photoresist), develop solutions, topcoat (TC)barrier layers, topcoat antireflective (TARC) layers, bottomantireflective (BARC) layers, sacrificial and barrier layers (hard mask)for etch stopping, etc. The nozzle 68 is coupled to a liquid supply unit(not shown) through a liquid supply line 70. In some embodiments, nozzle68 may be attached to the leading end of a nozzle scan arm 72 through anozzle holder 74. The nozzle scan arm 72 is mounted at the upper endportion of a vertical support member 76 that is horizontally movable ona guide rail 78 in one direction (e.g., in the Y-direction). Althoughnot shown in the figure, a drive mechanism (not shown) may be coupled tothe nozzle scan arm 72, the vertical support member 76 or the guide rail78 to move the nozzle 68 in the Y-direction. Other mechanisms (also notshown) can be used to move the nozzle 68 in the Z-direction and/or inthe X-direction. It will be recognized that the particular dispense andarm mechanisms and movements described herein are merely exemplary as awide variety of dispense techniques are well known in the art.

A cup 71 is provided to capture and collect a majority of the liquidmaterial ejected from the substrate by centrifugal forces generatedduring rotation by the spin chuck 64. The spin chuck 64 supports androtates (i.e., spins) the substrate about its central normal axisrelative to the cup 71, which is stationary. Liquid material ejectedfrom the substrate 59 and collected by the cup 71 is drained via a drainline 65 and drain unit (not shown). In some embodiments, an exhaust line67 and exhaust unit (not shown), such as a vacuum pump or other negativepressure-generating device may also be used to remove gaseous species(including but not limited to vapors released from substrate layersduring processing) from the processing space inside the cup 71.

Spin chuck 64 and drive mechanism 66 are disposed within an opening inthe cup 71. In some embodiments, an elevation mechanism, such as an aircylinder and an up-and-down guide unit, may be provided within drivemechanism 66 so the spin chuck 64 may move vertically relative to thechamber walls 62. The substrate can be delivered to the spin chuck 64 bya processing arm 61 through a loading/unloading opening 63 of fluiddispense system 60 in a direction 51 as shown in FIG. 1. The processingarm 61 may form a part of the fluid dispense system 60 or may be part ofa separate substrate transfer mechanism (not shown) for interacting withother process equipment. In some embodiments, the processing arm 61 maybe included within the main arm mechanism of a larger system fortransferring substrates between various process modules of the largersystem. In other embodiments, the processing arm 61 may be includedwithin other substrate processing systems. In some embodiments, theelevation mechanism can lift the drive mechanism 66 and/or the spinchuck 64 upwards to receive a substrate. Alternatively, the cup 71 maybe configured to move up-and-down, or may be configured to separate andwiden, to allow a substrate to be placed on the spin chuck 64.

It is noted that the fluid dispense system 60 shown in FIG. 1 is merelyone example processing system in which the monitoring techniquesdescribed herein may be used. Thus, the fluid dispense system 60 is notmeant to be limiting, but rather merely representative of one exampleprocessing system within which the monitoring techniques describedherein may be utilized. Further, though the fluid dispense system 60 isdescribed with reference to a system for processing substrates, whichmay in some embodiments be semiconductor wafers, it will be recognizedthat the techniques described herein may be utilized when processingother types of substrates. Thus, it will be recognized that themonitoring techniques described herein may be utilized within a widerange of substrate processing systems that apply liquid solutions tosubstrates.

Various embodiments of systems and methods for monitoring one or morecharacteristics of a substrate are disclosed herein. More specifically,the present disclosure provides various embodiments of utilizing opticalsensors to provide information regarding characteristics of a fluiddispense system. In one embodiment, the optical sensors may be camerasystems for obtaining video and/or still images from the substrate.However, the optical sensors may also include other optical sensors thatobtain spectral data, for a given wavelength or range of wavelengths,from a substrate. For example, other optical sensors suitable for usewithin the substrate inspection system disclosed herein include, but arenot limited to, spectrometers and sensors of laser-based transceivers.Thus, though described herein with regard to one embodiment of anoptical sensor which is a camera, it will be recognized that thetechniques described herein are equally applicable to other opticalsensors and not limited to cameras. Thus, the use of a camera as thesensor in the embodiments discussed below is merely exemplary andnon-limiting. The optical sensors may be utilized to collect videoimages, still images, spectrophotometric signals, optical power signals,etc.

As disclosed herein, a variety of hardware improvements and methods areprovided to improve the collection and analysis of the optical sensordata. More specifically, as described below, a wide variety of hardwarerelated techniques may be utilized, either in combination or singularly,to improve the collection of data using the optical sensor system (forexample a camera). These hardware techniques may include improvements tothe light source, improvements to the sensors of the optical sensor, therelationship of the physical orientation of the light source to theoptical sensor, the selection of certain pixels of the image foranalysis, and the relationship of the optical sensor frame rate with therotational speed of the substrate. These hardware improvements mayprovide improved film thickness measurement capabilities and reducesignal noise in the data.

Thus, the fluid dispense system 60 also includes a light source 92 andan optical sensor. In the embodiment of the figures the optical sensoris a camera 90 as shown in FIG. 1. As mentioned though, it will berecognized that the use of a camera is merely an exemplary embodiment ofany of a wide variety of optical sensors and is not meant to limit theoptical sensor to a camera embodiment. Further, as used herein, “camera”may refer to simply a camera or may be a more complex system thatincludes a camera and other electronics. The camera 90 may be utilizedto monitor the fluid dispense and coating process as described in moredetail herein below. The locations of the light source 92 and camera 90shown in FIG. 1 are merely exemplary and a wide variety of otherpositions may equally be utilized to allow the camera 90 to monitor thecondition of the substrate surface. FIGS. 2 and 3 provide a simplifiedtop view (excluding many of the details of FIG. 1) of the fluid dispensesystem 60 so as to better illustrate exemplary locations of the camera90 and light source 92. It will be recognized, however, that theselocations are merely exemplary and other locations may be utilized. Asshown in FIGS. 2 and 3 the substrate 59 is provided within the chamberwalls 62 of the processing chamber which has a loading/unloading opening63. FIG. 2 illustrates exemplary locations for locating the camera 90 inthe upper regions of the process chamber above the substrate. Morespecifically, FIG. 2 illustrates exemplary camera locations 201, 202,203, 204, 205, 206, and 207 for locating the camera 90. FIG. 3illustrates exemplary locations for locating the light source 92 in theupper regions of the process chamber above the substrate. Morespecifically, FIG. 3 illustrates exemplary light source locations 301,302, 303, 304, 305, 306 and 307 for locating the light source 92. Againit will be recognized that such locations of the camera and light sourceare merely exemplary and other locations may be utilized.

The techniques described herein are not limited to a particular cameraand light source type. The camera may be any of wide variety of types ofcameras designed to capture and/or store data from an image. The camerasmay collect still images and/or video images. A wide variety of camerasmay be utilized, including but not limited to, charged coupled device(CCD) image sensor cameras, complementary metal oxide semiconductor(CMOS) image sensor cameras, N-type metal-oxide-semiconductor (NMOS)image sensor cameras, indium gallium arsenide (InGaAs) image sensorcameras, indium antimony (InSb) image sensor cameras, etc. In someexamples, the light source may be ambient light, a light emitting diode(LED) light source, or a laser light source. In some embodiments, thelight source may typically be a light source of the visible spectrum orlonger. For example, light sources in the visible spectrum,near-infrared (NIR), shortwave-infrared (SWIR) and mid-infrared (MIR)are exemplary light sources. In one embodiment, an amber light source inthe visible spectrum may be utilized. In another embodiment, an infrared(IR) light source is utilized. In yet other embodiments, amulti-spectrum light source may be utilized. It will be recognized thatmany cameras may include integrated filters that block the IR spectrum.The use of such filters may be undesirable if the IR spectrum is desiredfor analysis.

As mentioned above, monitoring of a wide range of variables andconditions of the fluid dispense process may be achieved through theutilization of an optical sensor in the fluid dispense system. Variousmonitoring techniques are described below. It will be recognized thatthese techniques need not be utilized together but rather may beutilized individually. Alternatively, some or all of the techniques maybe combined for more thorough monitoring.

Coupled to (or even part of) the fluid dispense system 60 as shown ofFIG. 1 may be a controller 94 for setting and controller various processoperation parameters of the system. The controller 94 may be coupled tothe camera 90 and light source 92 as shown. The controller 94 may alsobe coupled as indicated by signal line 96 to any or all of a number ofthe components of the fluid dispense system 60 to receive informationfrom and/or to control the components. For example the controller 94 mayreceive information from and provide control information to the camera90, processing arm 61, spin chuck 64, drive mechanism 66, nozzle 68,nozzle scan arm 72, etc. The controller 94 may also be generallyconfigured to analyze various data collected by the fluid dispensesystem, and in some cases provide feedback control to various processoperation parameters. Thus, the techniques for data processing andsystem control described herein may be implemented by a controller 94.It is noted that the controller(s) 94 described herein can beimplemented in a wide variety of manners. In one example, the controllermay be a computer. In another example, controller 94 may include one ormore programmable integrated circuits that are programmed to provide thefunctionality described herein. For example, one or more processors(e.g., microprocessor, microcontroller, central processing unit, etc.),programmable logic devices (e.g., complex programmable logic device(CPLD)), field programmable gate array (FPGA), etc.), and/or otherprogrammable integrated circuits can be programmed with software orother programming instructions to implement the functionality describedherein for controller 94. It is further noted that the software or otherprogramming instructions can be stored in one or more non-transitorycomputer-readable mediums (e.g., memory storage devices, flash memory,dynamic random access memory (DRAM), reprogrammable storage devices,hard drives, floppy disks, DVDs, CD-ROMs, etc.), and the software orother programming instructions when executed by the programmableintegrated circuits cause the programmable integrated circuits toperform the processes, functions, and/or capabilities described herein.Other variations could also be implemented. It is noted that though thecontroller 94 is shown as part of the fluid dispense system 60, inalternate embodiments, the controller 94 may be separate from the fluiddispense system 60.

The analysis of a fluid dispense process with a camera may include awide range of techniques of analyzing and processing the images obtainedof the fluid dispense process. Such techniques may include analyzingstill images and/or analyzing video images obtained from the camera. Themonitoring of fluid dispense processes and the image obtained may beutilized for real time analysis/control and/or post process analysis.This image analysis may provide hardware and process feedback that mayotherwise not be available and can lead to improvements andoptimization. Image recording is an efficient method of data collectionthat can be done for every substrate. The image analysis can be used todetermine and/or control a variety of variables including filmthicknesses, critical dimensions, film uniformity, etc. In order toefficiently and accurately analyze images collected, automatedtechniques may be desirable.

The hardware utilized to monitor a spin coating process may be optimizedin a wider variety of manners so as to provide more accurate informationregarding the film formed on a substrate. More specifically, asdescribed below, a wide variety of hardware related techniques may beutilized, either in combination or singularly, to improve the collectionof data using the camera system. These hardware techniques may includeimprovements to the light source 92, improvements to the sensors of thecamera 90, the relationship of the physical orientation of the lightsource 92 to the camera 90, the selection of certain pixels of the imagefor analysis, and the relationship of the camera frame rate with therotational speed of the substrate.

Optimization of the hardware may address a variety of issues that arisewhen using an optical sensor during a spin coating process. In a spincoating process, it is possible to visually observe color changes on thewafer as the coated film decreases to its final coat thickness. Thesecolor changes are due to thin film interference reflectivity effects.For example when coating a resist layer on a substrate, these thin filminterference reflectivity effects are the effects of the resist/airreflected light wave with the resist/substrate reflected light wave. Asinterference of different wavelengths happen at different filmthicknesses, one may use the changing of the wavelength (and thus thecolor) that is having interference effect to monitor film thicknesschanges.

For example, FIG. 4 illustrates the impact on reflectivity as a filmthins during spinning. Note, in FIG. 4 the x axis represents resistthickness and the y axis illustrates the stack reflectivity. As shown inFIG. 4, reflectivity changes for three different exemplary processeshaving three different wavelength assumptions are illustrated. Morespecifically, plot 405, plot 410 and plot 415 illustrate differentcenter wavelengths assumptions for a Gaussian distribution light sourceassumption in simulation. In simulation, the reflectivity at a givenfilm thickness assumption is determined.

Depending upon the film thicknesses involved and the underlyingsubstrate conditions and materials, however, detection, discernment,analysis, and correlation of the reflected signal may be difficult. Forexample, for a typical resist/substrate refractive index relationship,an optical path length thru the resist film that is a half multiple ofthe wavelength of the light divided by the refractive index of thematerial will have constructive interference with the same wavelength oflight that is reflected off of the air/material surface and will havedestructive interference with that same light if the optical path lengthis a quarter multiple of the wavelength of light divided by therefractive index of the material. As material decrease thickness, thewavelength(s) of light that will constructively interfere change andthus results in an oscillation of the visible spectrum color (orintensity) seen by an observing camera (or sensor). For some LED lightsources, that can have a significant spectral range, if means howeverthat there are situations in which a greatest common multiple thicknessrelationship happens between two distantly different wavelengths havingconstructive interference simultaneously which mixes the color responseseen by the camera and leads to loss of signal.

First Embodiment Light Source Optimization

In a first embodiment, light source wavelength may be optimized toaddress some of the problems discussed above. Specifically, longerwavelengths of light will assist with preventing multiple wavelengthssimultaneously having constructive interference effects (effects whichinduce more noise in the thin film interference results). Thus, for thesame spectral range, for example, the light source may be chosen to benear the absorption capabilities/limitation of the optical sensor (onthe high wavelength side). This provides benefits from an increase insignal to noise as the nature of the periods of constructive anddestructive interference has increased which means it is less likely tohave the situation of the greatest common multiple creating thicknessesin which multiple wavelengths from the light source are havinginterference simultaneously. For example in one illustrative embodiment,a camera having optical sensing capabilities of sensing wavelengths of arange of 400 nm to 850 nm (or approximately 1050 nm if no IR filter isin the camera assembly) may be utilized. However, the light source maybe chosen to have wavelengths in the 600 nm to 900 nm range thusreducing number of wavelengths simultaneously having constructiveinterference effects. For example, a CMOS type camera with IR band passfilter having a sensing range of 400 nm to 850 nm may be utilized with aNIR LED type light source having an output range of 775 nm to 900 nm. Inanother example, a CMOS type camera having a sensing range of 400 nm to850 nm may be utilized with an amber LED type light source having anoutput range of 500 nm to 800 nm. In this manner, light source chosenmay be limited to a light source that provides light only at an upperrange of the capabilities of the camera. In one example, the lightsource may operate at the upper 50% of the camera range, and in anotherexample more preferably in the upper 20% range of the camera. Thus, alight source may be chosen that provides a range of wavelengths of lightthat is smaller than the range the camera is capable of sensing. Moreimportantly, the light wavelengths are provided at an upper end of thecamera sensing capabilities.

Second Embodiment Camera Sensor Optimization for Given Light Source

In a second embodiment, the camera and the light source may beco-optimized. It is noted that CMOS/CCD cameras are relativelyinexpensive and prevalent digital camera technology of the visiblespectrum. However, CMOS/CCD cameras absorption capabilities often extendinto the NIR (often to approximately 1050 nm). It is noted that the nearinfrared spectrum may be characterized by wavelengths of approximately700 nm to 1400 nm. Many camera manufacturers however include a shortpass filter into the camera assembly to cut the IR light allowed intothe camera to prevent IR noise from affecting the visible spectrumpicture fidelity. For spin coating analysis, significant benefit isfound by using a camera without the NIR filter and matching the camerawith a NIR light source. Similarly, using a SWIR (often characterized aswavelengths of approximately 1400 nm to 3000 nm) light source andmatching it with a SWIR camera (for example an Indium Gallium Arsenide(InGaAs) based camera) could have similar benefit. Thus, the benefitsdiscussed above regarding the first embodiment may be extended byutilizing cameras that are not limited by filters to exclude longerwavelengths and correspondingly using light sources that have the longerwavelengths in question. In this manner, the light source and the camerautilized may be optimized together to provide a system of providinglonger wavelengths and detecting those longer wavelengths, again thusminimizing greater interference effects that may occur with shorterwavelengths.

Third Embodiment Filtering of Light

In a third embodiment, the spectral range of the light may be limited bythe use of filters. As noted above, it is desirable to limit theinstances in which multiple wavelengths are constructively interferingsimultaneously because limiting such instances provides a better signalquality to the color (or intensity) oscillation seen by the opticalsensor (in this example a camera). Thus, limiting the spectral range ofthe light utilized in the system may limit the number of wavelengthswhich are constructively interfering and therefore provide improvedsignal results. Therefore filters may be used that are tailored to cutthe spectral range of our light source. The light filtering may beaccomplished through a variety of types of filters including short passfilters, long pass filters, or band pass filters. The filter can beincorporated into the optical light path in a variety of places withinthe system. In one example, the filter may be located between the lightsource and substrate. In another example, the filter may be locatedbetween the substrate and the sensor. In such a case, it may bedesirable to locate the filter in front of (or in close proximity to)the sensor as the exemplary example. The smallest spectral range thatstill allows a viable absorption signal to be detected and discerned bythe sensor may be optimal. For example, in one embodiment, filtering maybe performed to a wavelength range of 40 nm, even more narrowly to awavelength range of 10 nm range, and even more preferred to a wavelengthrange of 5 nm.

Absorption properties of the material itself can also impact whichwavelengths that can viably be used. Thus, an alternative embodiment ofthe spectral range/light source co-optimization involves the pairing ofan initially broadband light source with a spectral filter wheel. Thespectral filter wheel can provide a variety of filters that can berotated into the optical path depending upon the desired filtering mostsuitable for the particular film coating material and underlyingsubstrate combination. In one embodiment, the filter wheel may include aplurality of band pass filters. In this manner a common hardware setupmay be provided that allows the selection of an optimum spectral bandfor a variety of different material absorption properties which may beencountered during the use of the system. Such a system provides processflexibility. Further, the choice of any given spectral filter may beincorporating into the spin coating recipe for a particular coatingmaterial at a particular point of the substrate process flow. Thus forexample, a broadband light source may be utilized in conjunction with afilter wheel that has band pass filters of passing 650 nm to 690 nm witha first filter, 710 nm to 750 nm with a second filter, 770 nm to 810 nmin a third filter, and 830 nm to 870 nm in a fourth filter. The bandpass ranges are merely exemplary however. Further, the band pass rangeutilized may be dependent upon the film thicknesses being monitored(higher thickness may require narrower ranges for the band pass).

An another alternative use of a spectral filter wheel concept would be aseries of band pass filters centered around the same wavelength (forexample a 40 nm band pass filter, a 20 nm band pass filter, 10 nm bandpass filter, and a 5 nm band pass filter, all the filters centeredaround the same wavelength, for example 850 nm. Such a filter wheel maybe utilized to address differing film thicknesses. One may use thelowest spectral range required for the signal (thicker films using moreaggressive narrower band pass filters and thinner films using lessaggressive wider band pass filters, if any at all. However, usingsmaller ranged band pass filters limits the amount of light into camerasystem. Thus using a 5 nm band pass filter exclusively may make use ofthat video for general reviewing purposes nearly impossible without anexceptionally bright light source. Thus, one may inset a blanknon-filtered section into filter wheel. One such use of a non-filteredsection may be when using a very thick film that needs 5 nm band passfilter to see the signal. In such case, the filter wheel may oscillatebetween the 5 nm band pass filter and the blank at half frequency ofcamera to have useful frames (the blank filtered every other frame) forgeneral review of processing conditions as well as still have the bandpass signal available for film thickness monitoring (by using thefiltered frames). It will be recognized that providing four selectablefilters is merely exemplary and the system may be configured to allowfor more or less filters. Likewise, the use of a filter wheel is merelyexemplary and other mechanisms may be utilized to selectively place adiffering filter within the optical path between the light source andthe optical sensor as the techniques described are not limited to theuse of a wheel.

Fourth Embodiment Orientation of the Light Source and the Camera

In a fourth embodiment, the physical location of the light source andcamera are optimized together. More specifically, as a reflectivitysignal is being collected, the reflectivity signal strength may bemaximized by ensuring the 0^(th) order reflection of the light sourceoff the substrate is being collected into the optical sensor (forexample a camera). Doing this also mitigates other effects, which areexperienced in other sensor/light source orientation relationships suchas light diffraction effects from underlying highly reflective gratings.To ensure and maximize the reflectivity signal, the physical locationsof the light source and camera may be adjusted. Specifically, it may bedesirable to 1) maintain a similar angle to a reference plane (that isparallel to the substrate plane) of the light source and the opticalsensor, 2) maintain a similar distance relationship of the light sourceto the center of substrate and the center of substrate to optical sensorand 3) to have the optical sensor positioned 180 degrees diagonallyacross from light source. Exemplary locations illustrating theseconcepts are shown in FIGS. 5 and 6. As shown in FIG. 5, a light source92 and camera 90 are placed with reference to a substrate 59. Thelocations of the light source 92 and camera 90 may be chosen so that theangle of incidence 505 and angle of incidence 510 of the figure aresimilar. In one embodiment, the angles of incidence are within 20degrees of each other, in a more preferred embodiment within 10 degrees,and in an even more preferred embodiment are approximately the same.Further, the distance from the light source 92 to the center of thesubstrate 59 may be d, and the distance from the camera 90 to the centerof the substrate 59 may be the same distance d as shown in FIG. 5. Inone embodiment, the distances may be within 10% of each other and inanother embodiment 5% and in a more preferred embodiment substantiallythe same.

Further, as shown in FIG. 6 it may be desirable to have the light source92 and camera 90 located across from each other. In one embodiment, thelight source 92 and camera 90 are substantially 180 degrees diagonalfrom each other, and in another embodiment located within 10 degrees ofbeing 180 degrees diagonal from each other and in another embodimentwithin 20 degrees of being 180 degrees diagonal from each other. It isnoted that the closer to being 180 degrees diagonal generally providesimproved results. FIG. 6 illustrates two exemplary pairings of locationsproviding for such diagonal relationship. For example, the camera 90 maybe placed at location 605A and the light source 92 may be placed atlocation 605B. This pairing of locations provides the desired 180 degreerelationship. Likewise, alternative locations 610A and 6106 may bechosen for the light source 92 and camera 90.

It will be recognized that the arrangements of FIGS. 5 and 6 are merelyexemplary locations to provide the angle and distance benefits describedabove and other locations may be chosen to achieve the same angle anddistance results.

Fifth Embodiment Pixel Selection

A fifth embodiment relates to the selection of the pixels from whichdata is collected in a frame of the substrate. For example, all pixelsthat represent the substrate may be used for the benefit of pixelaveraging out any small differences in pixel absorption properties ofthe camera as well as sources of image noise (vibration, moving arms,slight changes of light source intensity, outside coat cup lightenvironment, etc.). However, inclusion of sources of image noise mightnot be desirable. Also, use of all pixels would include pixels thatrepresent non 0^(th) order reflections. However, use of only a subset ofpixels may address these issues and provide more accurate data. Forexample, if the light source/light spectral range is not well alignedwith camera absorption properties (e.g. the spectral tail of lightsource is the only thing that is being absorbed by camera) thenaveraging all of the pixels from a substrate leads to a loss of signal.One way to address this issue and to regain the signal is to limit thepixels selected to only those pixels in and/or in close proximity to theobservable primary reflection of the light source in the camera frame.Such pixels in and/or in close proximity to the observable primaryreflection of the light source in the camera frame represent the pixelsthat are most representing the 0^(th) order reflection of our lightsource. Similarly, selecting only a subset of pixels may allow for theexclusion of regional based noise sources. Thus, use of a selectedsubset of pixels may provide an improved signal from which dataregarding the conditions on the substrate may be extracted. The size ofarea that the subset of pixels may be limited to may be highly dependentupon the light source and camera combination utilized.

FIG. 7 illustrates exemplary effects of selecting only a subset ofpixels for analysis. As shown in FIG. 7, plots of the average gray scaleintensity (after removing the average frame from shortly after dispensestart to end of processing) for a series of frames that are obtainedover time from the camera data (thus, the x-axis being collected overtime). Plot 705 represents the intensity obtained over the entirecollected image from the camera. Plot 710 represents the intensityobtained when the data is limited to a region that corresponds to thesubstrate. It can be seen that for both of these plots, noise sourcesand the wide range of the reflections provide large areas of noise wherethe signal loses its cyclical nature over many frames. Plot 715 and Plot720 are plots in which only a subset of pixels of the substrate areanalyzed. The size of area from which the subset of pixels may belimited to may be highly dependent upon the light source and cameracombination utilized. For example, when using an IR LED light source at850 nm and a first camera with an integrated IR filter, extreme pixelmasking to narrowly select the location of reflection on the lightsource may be desirable, for example limiting the pixels to 10% or even5% or less of the pixels that correspond to the substrate area. However,in another embodiment utilizing different camera (CMOS camera) withoutan IR band pass filter and an IR LED source at 850 nm, pixel masking maynot be to the same level as the prior example to provide a determinationof the reflected signal (though masking may still increase the amplitudeof the detected signal). For example, pixel masking of onlyapproximately half the pixels that correspond to the substrate area maybe utilized. As seen from the plots, the use of a subset of pixelsprovides a signal with better noise characteristics.

Sixth Embodiment Camera Frame Rate and Substrate Rotational Speed

In a sixth embodiment, problems caused by underlying patterns on thesubstrate being coated are addressed. For example, underlying reflectivesurfaces may create significant diffraction effects as the patternrotates during the coating process. Thus, an ever changing underlyingpattern is seen by the camera. These diffraction effects may limit theability to observe the characteristics of the film being coated. Morespecifically, the diffraction effects (from the underlying pattern) arechanging with each frame of the camera because the relationship of thelight source to the orientation of the grating inducing the diffractioneffects is changing with each frame. In this case it will be difficultto know if a change in a pixel is due to the change in thickness of thecoated material or the change in diffraction effect due to the change insubstrate orientation. FIGS. 8A-8C illustrate this problem. FIG. 8Aillustrates a first frame of camera data for a substrate 805 and thefirst portion 810 of the substrate 805 for which pixel data is collectedin the first frame. Due to the rotation of the substrate 805, in thesecond frame of camera data, the pixel data collected corresponds to asecond portion 815 of the substrate 805. Similarly, in the third frameof camera data, the pixel data collected corresponds to a third portion820 of the substrate 805. Thus, the collected pixel data will representdiffering orientations of the underlying pattern on the substrate 805.

According to this sixth embodiment, the technique disclosed hereinmatches the frame rate (or a multiple of the frame rate) of the camerato the RPMs of the coat process. By synchronizing this relationship, thecamera will be looking at the same orientation of the substrate in eachframe being captured by the camera. Therefore, even though diffractionis still induced by the grating, it is consistent frame to frame andthus can be subtracted to see the underlying reflectivity signal relatedto thickness changing. In one embodiment, the sampling rate of theoptical sensor and the spin rate of the substrate are synchronizedwithin 5%, in another embodiment within 1% and in a more preferredembodiment are substantially the same. While this embodiment discussesframe rate optimization relative to a camera system, similar samplingfrequency optimization could be employed for other sensor methods. Thus,it will be recognized that though described with regard to frames of acamera, the correlation of the sampling rate of the optical sensor tothe rotational spin rate of the substrate may be performed for anyoptical sensor. FIGS. 9A-9C illustrate the impact of matching the sensorsampling rate to the rotational speed of the substrate. Morespecifically, FIG. 9A illustrates a first frame, FIG. 9B illustrates asecond frame, and FIG. 9C represents a third frame. Due to the matchingof the camera frame rate and the rotational spin rate of the substrate,the selected pixels of the substrate are a same common portion 825 ofthe substrate 805.

It will be recognized that the substrates described herein may be anysubstrate for which the substrate processing is desirable. For example,in one embodiment, the substrate may be a semiconductor substrate havingone or more semiconductor processing layers (all of which together maycomprise the substrate) formed thereon. Thus, in one embodiment, thesubstrate may be a semiconductor substrate that has been subjected tomultiple semiconductor processing steps which yield a wide variety ofstructures and layers, all of which are known in the substrateprocessing art, and which may be considered to be part of the substrate.For example, in one embodiment, the substrate may be a semiconductorwafer having one or more semiconductor processing layers formed thereon.Although the concepts disclosed herein may be utilized at any stage ofthe substrate process flow, the monitoring techniques described hereinmay generally be performed before, during or after a substrate issubject to a fluid dispense operation.

FIGS. 10-15 illustrate exemplary methods for use of some of theprocessing techniques described herein. It will be recognized that theembodiments of FIGS. 10-15 are merely exemplary and additional methodsmay utilize the techniques described herein. Further, additionalprocessing steps may be added to the methods shown in the FIGS. 10-15 asthe steps described are not intended to be exclusive. Moreover, theorder of the steps is not limited to the order shown in the figures asdifferent orders may occur and/or various steps may be performed incombination or at the same time.

FIG. 10 illustrates an exemplary method of monitoring one or morecharacteristics of a fluid dispense system. The method comprises step1005 of providing a substrate within the fluid dispense system; step1010 of providing an optical sensor, the optical sensor having anoptical range of detected wavelengths; step 1015 of providing a lightsource, the light source providing wavelengths in only an upper 50percent of the optical range; and step 1020 of obtaining data from theoptical sensor to monitor a condition of a fluid dispensed on thesubstrate.

FIG. 11 illustrates an exemplary method of monitoring one or morecharacteristics of a fluid dispense system. The method comprises step1105 of providing a substrate within the fluid dispense system; step1110 of providing a camera, the camera configured to receive wavelengthsof light in the near infrared spectrum or higher; step 1115 of providinga light source, the light source providing wavelengths in the nearinfrared spectrum or higher; and step 1120 of obtaining data from thecamera at wavelengths in the near infrared spectrum or higher to monitora condition of a fluid dispensed on the substrate.

FIG. 12 illustrates an exemplary method of monitoring one or morecharacteristics of a fluid dispense system. The method comprises step1205 of providing a substrate within the fluid dispense system; step1210 of providing a light source having a spectral range of wavelengths;step 1215 of providing an optical sensor, the optical sensor receivinglight from the light source that is reflected off the substrate; step1220 of providing a filter in an optical light path between the lightsource and the optical sensor; the filter narrowing a received spectralrange of light received by the optical sensor; and step 1225 ofobtaining data from the optical sensor to monitor a condition of a fluiddispensed on the substrate.

FIG. 13 illustrates an exemplary method of monitoring one or morecharacteristics of a fluid dispense system. The method comprises step1305 of providing a substrate within the fluid dispense system; step1310 of providing a light source; step 1315 of providing an opticalsensor, the optical sensor receiving light from the light source that isreflected off the substrate; step 1320 of arranging a physical locationof the optical sensor and the light source so that a 0^(th) orderreflection of the light that is reflected off the substrate is receivedby the optical sensor; and step 1325 of obtaining data from the opticalsensor to monitor a condition of a fluid dispensed on the substrate.

FIG. 14 illustrates an exemplary method of monitoring one or morecharacteristics of a fluid dispense system. The method comprise step1405 of providing a substrate within the fluid dispense system; step1410 of providing a light source; step 1415 of providing a camera, thecamera receiving light from the light source that is reflected off thesubstrate; and step 1420 of coupling a controller to the camera, thecontroller configured to receive data from the camera regarding lightreflected from the substrate when one or more fluids are dispensed onthe substrate, the controller processing the data so as to selectivelyconsider only a subset of pixels of the data from the camera to monitora condition of a fluid dispensed on the substrate.

FIG. 15 illustrates an exemplary method of monitoring one or morecharacteristics of a fluid dispense system. The method may comprise step1505 of providing a chuck within the fluid dispense system, the chuckbeing configured to spin; step 1510 of providing a substrate within thefluid dispense system; step 1515 of spinning the chuck at a firstrevolutions per minute; step 1520 of providing a light source; step 1525of providing an optical sensor, the optical sensor receiving light fromthe light source that is reflected off the substrate, the optical sensorsampling received light at a first sampling rate; step 1530 ofsynchronizing the first revolutions per minute to the first samplingrate; and step 1535 of obtaining data from the optical sensor to monitora condition of a fluid dispensed on the substrate.

Further modifications and alternative embodiments of the inventions willbe apparent to those skilled in the art in view of this description.Accordingly, this description is to be construed as illustrative onlyand is for the purpose of teaching those skilled in the art the mannerof carrying out the inventions. It is to be understood that the formsand method of the inventions herein shown and described are to be takenas presently preferred embodiments. Equivalent techniques may besubstituted for those illustrated and described herein and certainfeatures of the inventions may be utilized independently of the use ofother features, all as would be apparent to one skilled in the art afterhaving the benefit of this description of the inventions.

What is claimed is:
 1. A method of monitoring one or morecharacteristics of a fluid dispense system, the method comprising:providing a chuck within the fluid dispense system, the chuck beingconfigured to spin; providing a substrate within the fluid dispensesystem; spinning the chuck at a first revolutions per minute; providinga light source; providing an optical sensor, the optical sensorreceiving light from the light source that is reflected off thesubstrate, the optical sensor sampling received light at a firstsampling rate; synchronizing the first revolutions per minute and thefirst sampling rate; and obtaining data from the optical sensor tomonitor a condition of a fluid dispensed on the substrate.
 2. The methodof claim 1, wherein the optical sensor is a camera.
 3. The method ofclaim 2, wherein the camera is a video camera.
 4. The method of claim 2,wherein the synchronizing of the first revolutions per minute and thefirst sampling rate provides for a plurality of frames of data to becollected by the camera so that the substrate is in a same rotationalorientation for each of the plurality of frames.
 5. The method of claim4, wherein synchronizing the first revolutions per minute and the firstsampling rate provides consistent diffraction effects frame to frame. 6.The method of claim 5, further comprising subtracting the consistentdiffraction effects to analyze an underlying reflectivity signal.
 7. Themethod of claim 6, wherein analysis of the underlying reflectivitysignal provides fluid thickness information.
 8. The method of claim 1,wherein the synchronizing of the first revolutions per minute and thefirst sampling rate provides for a plurality of sets of data to becollected by the optical sensor so that the substrate is in a samerotational orientation for each of the plurality of sets of data.
 9. Themethod of claim 8, wherein synchronizing the first revolutions perminute and the first sampling rate provides consistent diffractioneffects between data set to data set.
 10. The method of claim 9, furthercomprising subtracting the consistent diffraction effects to analyze anunderlying reflectivity signal, wherein analysis of the underlyingreflectivity signal provides fluid thickness information.
 11. The methodof claim 1, wherein the sampling rate of the optical sensor and the spinrate of the substrate are synchronized within 5%.
 12. The method ofclaim 1, wherein the sampling rate of the optical sensor and the spinrate of the substrate are synchronized within 1%.
 13. A fluid dispensesystem for coating a film on a substrate, the fluid dispense systemcomprising: a spin chuck capable of holding the substrate; a nozzlecapable of dispensing one or more fluids onto the substrate; an opticalsensor; a light source; and one or more controllers coupled to theoptical sensor and the spin chuck, the one or more controllersconfigured to synchronize a rate of spinning of the spin chuck and asampling rate of the optical sensor, wherein at least one of the one ormore controllers is configured to receive data from the optical sensorregarding light reflected from the substrate when the one or more fluidsare dispensed on the substrate.
 14. The fluid dispense system of claim13, wherein the optical sensor is a camera.
 15. The fluid dispensesystem of claim 14, wherein the synchronizing of the rate of spinning ofthe spin chuck and the sampling rate provides for a plurality of framesof data to be collected by the camera so that the substrate is in a samerotational orientation for each of the plurality of frames.
 16. Thefluid dispense system of claim 15, wherein the one or more controllersis configured to subtract the diffraction effects to analyze anunderlying reflectivity signal, wherein analysis of the underlyingreflectivity signal provides fluid thickness information.
 17. The fluiddispense system of claim 15, wherein the sampling rate of the opticalsensor and the spin rate of the substrate are synchronized within 5%.18. The fluid dispense system of claim 13, wherein the sampling rate ofthe optical sensor and the spin rate of the substrate are synchronizedwithin 5%.
 19. The fluid dispense system of claim 18, wherein theoptical sensor is a video camera.
 20. The fluid dispense system of claim13, wherein the sampling rate of the optical sensor and the spin rate ofthe substrate are synchronized within 1%.